What Digital Asset Management or Media Asset Management software do you use and why?

Im looking for a way to move from just file structure organization to some sort of software that will allow me to easily sort and search photos and videos, and preferably interface with a website based on ExpressionEngine.

Only a few people would need access to the system. We are currently storing it on shared network drives.

How tech savvy is your staff? Do you have someone who could handle running an Open Source DAM from an Ubuntu server, or someone who could create your own in-house DAM using WordPress and Custom Post Types/Custom Taxonomy?

Also, and maybe more importantly, have you thought about how and who will be entering your media into your DAM? You can have the most perfect software solution in the world but if your processes aren't solid the DAM will be an unfindable mess. Consistency is crucial.